Experimental and theoretical determination of low electron energy loss spectra of Ag and Ru

We show the experimental and calculated q -dependent low energy loss electron energy loss spectrum of Ru and Ag. The spectra were calculated within the time-dependent density-functional theory including local-field effects. For Ag, the momentum transfer was parallel to the (1 1 0) direction. For Ru the three main directions (0 1 0), (1 1 0) and (0 0 1) were investigated. The agreement between theory and experiment is very good for Ag and for momentum transfers parallel to the (0 0 1) direction of Ru. For momentum transfers parallel to the in-plane directions (1 1 0) and (0 1 0) the agreement for Ru is not satisfactory, which could be attributed to relativistic effects or to strong localization of the 4d states of Ru.